The present invention relates to a procedure for setting up a call in telephone network using a predetermined right of use of the telephone network.
An essential part of operating a telephone network is the system of charging the user for the calls. There are several different prior-art methods and systems that allow a telephone network operator to invoice a customer using the operator""s telephone network in advance. In a certain system, prepaid call cards or equivalent are used, in which case the customer buys at a resale point a call card bearing stored conversation time data corresponding to the price of the call card. For the use of a call card, a terminal comprising equipment for reading the call card and updating the conversation time data on it are needed. On the other hand, it would be possible to use e.g. DTMF tones to transmit the information that the customer using the telephone network has paid for the call in advance. However, such solutions involve the problem that in countries having a low level of development of telephony there is but a small number of DTMF telephones in use, so this system cannot be used to implement services intended for a large number of users. Moreover, reliable identification of pulse dialling signals is not possible because of poor connections or identification of tones is not possible because of poor quality of connections and terminal equipment. A further problem in the countries referred to is that telephone exchanges rarely verify the correctness of the A-subscriber number of the calling subscription. In the call record, only the A-subscriber number sent by a private automatic branch exchange is recorded, so the charge for the call is debited to this A-subscriber number. However, it is possible to program the PABX so that the A-subscriber number sent to the exchange will be changed e.g. once every hour. In this case, a series of different: A-subscriber numbers can be selected to be sent by turns, which means that the charges for the calls will also be collected with bills corresponding to these A-subscriber numbers.
The object of the present invention is to eliminate the problems described above.
A specific object of the present invention is to disclose a procedure that makes it possible to implement an arrangement useful for customers and telecommunication network operators, a so-called prepaid service, in which the customer pays in advance for conversation time to be used. A further object of the invention is to disclose an arrangement that allows such a prepaid service to be implemented even in countries underdeveloped in respect of telephony. Yet another object of the invention is to enable telephone services to be made available even to customers not considered creditworthy, so that they could be offered conversation time without advance payment.
A further object of the invention is to prevent the kind of abuse described above, in which the A-subscriber number sent by a PABX is changed e.g. hourly. It can be further stated about the objects of the invention that a service achieved by applying the procedure of the invention is easy to implement in a technical sense and economical to both operator and customer.
As for the features characteristic of the invention, reference is made to the claims.
In call setup according to the procedure of the invention for setting up a call in a telephone network using a predetermined right of use of the telephone network, the subscriber number of the calling subscriber, i.e. A-subscriber, and the subscriber number of the called subscriber, i.e. B-subscriber, are sent into the telephone network. These subscriber numbers can be sent in the fields normally reserved for them in the call setup signalling. Further, in the procedure of the invention, the A-subscriber""s right of use is verified before call setup. This generally means checking that the A-subscriber has either paid beforehand for his/her right of use e.g. via a call card or that the A-subscriber has a right of use based on credit.
According to the invention, in conjunction with call setup, the procedure adds to the B-subscriber number to be sent into the telephone network a character string from which it can be established in the telephone network that the caller is an A-subscriber who is using a predetermined right of use, and which comprises an A-subscriber-specific identifying code. In practical call setup, this character string can be added e.g. by entering it before the B-subscriber number via the terminal device, or, on the other hand, the character string can be added automatically e.g. by using a sequence programmed in the PABX. Further, according to the invention, the A-subscriber""s right of use is verified in the telephone network on the basis of the A-subscriber-specific identifying code. Now, if the A-subscriber has a right of use, i.e. the A-subscriber has paid for use of the telephone network in advance, then the call setup process between the A and B subscribers is continued in the normal manner. In a preferred case, the A-subscriber""s right of use is verified by identifying the subscriber based on the A-subscriber number and comparing the identifying code attached to the B-subscriber number with the A-subscriber""s identifying codes in the telephone network. In addition, if the identifying code is correct, a check is carried out to establish whether the A-subscriber has a valid right of use. If these checks indicate that the A-subscriber""s code is not correct or that the A-subscriber has no valid right of use, then the call can be directed to a predetermined subscriber number from which the A-subscriber can be given a notice either about the incorrectness of the identifying code or about the insufficiency of the balance on his/her account and asked to make a further payment.
As compared with prior art, the procedure of the present invention provides the advantage that prepaid calls can be made available to the customers of a teleoperator without the use of separate call cards or corresponding media. Further, the invention makes it possible to realise an arrangement that works even in countries underdeveloped in respect of telephony and that can be utilised to implement prepaid telephone services.
A further advantage of the present invention is that the invention makes it possible to prevent the practice of a certain kind of deceit in the telephone network. The invention allows the subscriber numbers in the telephone network to be protected by means of identifying codes so that a given subscriber number can only be used if one knows the identifying code associated with it. This is particularly relevant in a situation where a PABX with a character string according to the invention preprogrammed in it is used, which character string is sent into the network and used to identify the caller as an A-subscriber utilising a predetermined right of use.
In an embodiment of the present invention, the expenditure of the right of use or balance available to the subscriber is monitored. If the balance or right of use is exhausted, either the caller is requested to deposit more money, whereupon the call is broken off, or the call is simply broken off. In a preferred embodiment, after a normal call, the balance or right of use associated with the A-subscriber number must be updated and the identifying code used must be removed from the database. In this case, the identifying code is an expendable one and a new identifying code must be used every time when a new call is set up. On the other hand, in an embodiment of the invention, the identifying code may be valid for e.g. for a given predetermined period of time, in which case, by using this identifying code, the subscriber can make an unlimited amount of calls, provided that the balance or right of use has not been exhausted.
The right of use can be defined in terms of available conversation time a monetary balance dependent on conversation time, number of units or equivalent. Further, the right of use is preferably decreased on the basis of data stored with the call data, such as location of the B-subscriber, i.e. whether the call is a local call or a long-distance call, duration of the call, starting time of the call or corresponding data.
Further, in an embodiment of the invention, a subscriber number may be associated with several series of identifying codes. In this case, each series of identifying codes comprises one or more identifying codes, each series of identifying codes being used by sending a valid identifying code from the identifying code series in question. This is particularly advantageous in cases where a single terminal and a single subscriber number are used by more than one user. Thus, a specific series of identifying codes and an associated right of use can be defined for each user.